Electrical systems for electric vehicles

Abstract

The present disclosure provides an on-board charger with integrated motor drive to reduce the number of components in the electrical system of an electric vehicle. In charging mode, the motor and motor drive inverter are utilized as part of the on-board charger, thereby reducing the number of components. By controlling relays, the electrical connections of the system can be reconfigured depending on the operating mode. In one aspect, the motor and motor drive inverter act as a boost PFC, a current regulator, or both.

Description

[Technical Field]

[0001] [Related Applications] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 162,694, filed March 18, 2021, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present disclosure relates to implementing an on-board charger that utilizes components of the motor drive circuit to reduce the cost and volume of the electrical system in an electric vehicle. [Background technology]

[0003] Electric vehicles are powered by electric motors rather than internal combustion engines. Electric motors do not emit greenhouse gases, whereas internal combustion engines do, causing air pollution and global warming. As environmental protection becomes increasingly important, interest in electric vehicles is rapidly increasing.

[0004] FIG. 1A shows a conceptual diagram of an electric vehicle electrical system 10. The system 10 includes a motor 11, a motor drive 12, a battery 13, and a vehicle Full of content The electrical system 10 includes an electric appliance 14, and an AC input 15. The electric motor 11 can be connected to the mechanical system of the electric vehicle. The electric motor 11 converts electrical energy within the system 10 into mechanical energy to rotate the wheels of the electric vehicle. The motor drive 12 supplies electrical energy from a battery 13 to the motor 11. The on-board charger 14 supplies electrical energy from the external AC input 15 to the battery 13. It should be noted that the electrical system 10 therefore includes components of both the motor drive 12 and the on-board charger 14.

[0005] 1B and 1C show the direction of electrical energy flow within the system 10 in the drive mode and the battery charging mode, respectively. In the drive mode, as shown in FIG. 1B, electrical energy is supplied from the battery 13 to the motor 11. The battery 13 is discharging, and the on-board charger 14In the battery charging mode, as shown in FIG. 1C, electrical energy is supplied from the AC input 15 to the battery 13. The battery 13 is charging, and the motor drive 12 is not operating. Note that in this state, the motor drive 12 and the on-board charger 14 in the electrical system 10 are not operating simultaneously. That is, only the motor drive 12 is active in the driving mode, and only the on-board charger 14 is active in the battery charging mode. Because the motor drive 12 and the on-board charger 14 are not operating simultaneously, the motor 11 and / or the motor drive 12 must be utilized as part of the on-board charger 14 to reduce the number of components in the system 10.

[0006] 2A shows an exemplary schematic circuit of a conventional electrical system 20 for an electric vehicle with a three-phase motor. The electrical system 20 includes a three-phase motor 21, a motor drive inverter 22, a battery 23, an on-board charger 24, and an AC input 25. The three-phase motor 21 and the motor drive inverter 22 are connected to the right side of the battery 23 via relay R2. Due to safety concerns, relays R1 and R2 are essential so that the battery 23 can be physically disconnected from the system 20 when the system 20 is not operating.

[0007] The three-phase motor 21 has three windings embedded in a stator assembly. Each stator winding can be electrically represented as an inductor. The motor drive inverter 22 includes three identical half-bridge legs with switches S1, S2, ..., S6. The switching node of each half-bridge leg is connected to one end of the stator winding of the motor 21. The other end of the stator winding is connected to a single node called the neutral point. The motor drive inverter 22 is Gilet The torque is controlled by adjusting the duty cycle of the motor to control the motor phase current. The on-board charger 24 has two stages: an AC / DC power factor correction (PFC) stage 241 and an isolated DC / DC converter stage 242. The AC / DC PFC stage 241 adjusts the shape of the input current so that the charger achieves a high power factor and low total harmonic distortion of the input current.

[0008] A boost converter is commonly used in AC / DC PFC stage 241 due to its continuous input current and ease of control. In this example, AC / DC PFC stage 241 includes rectifier diodes D1, D2, D3, and D4, a boost inductor L PFC , boost switch S B1 , and boost diode D5. Link capacitor C O,PFC The output voltage of the AC / DC PFC stage 241 over the input voltage V is quasi-DC with low frequency ripple. The ripple is caused by the large power ripple inherent in single-phase systems. AC When is zero, the input power is zero and the input voltage V AC When is maximum, the power is also maximum. Therefore, the power flow in the AC / DC PFC stage varies over the entire line cycle. Since the AC voltage has two zero crossings, the PFC power varies at twice the grid frequency.

[0009] A DC / DC converter stage 242 follows the AC / DC PFC stage 241, providing an isolation barrier and a constant DC charging current to the battery 23. For isolated DC / DC converters, the LLC resonant converter topology is currently widely used due to its high efficiency with a small number of components. Figure 2A shows the main switch S INV1 and S INV2 , resonant inductor L R , resonant capacitor C R1 and C R2 , Trans T R , rectifier diode D R1 and D R2 , and Biko Capacitor C IN2 The figure shows an isolated half-bridge LLC resonant converter including an on-board charger with three main functions: power factor correction, isolation, and DC charging current regulation.

[0010] Figures 2B and 2C illustrate the drive mode and battery charge mode, respectively, of the conventional electrical system of Figure 2A. Figure 2B illustrates drive mode operation in which relay R2 is closed and relay R1 is open, so that the battery 23 is connected only to the motor 21 and motor drive inverter 22. The on-board charger 24 is turned off and therefore inactive. Energy stored in the battery 23 is gradually depleted by driving the vehicle using the system 20. Figure 2C illustrates charge mode operation in which relay R2 is open and relay R1 is closed, so that the battery 23 is connected only to the on-board charger 24. The motor drive inverter 22 is turned off and the motor 21 is not operating.

[0011] References [1] SRMeher, S. Banerjee, BTVankayalapati, and RKSingh, "A Reconfigurable On-Board Power Converter for Electric Vehicle With Reduced Switch Count," IEEE Trans.on Vehicular Technology, vol.69, no.4, Apr.2020. [2] M. Tong, M. Chenc, W. Hua, and S. Ding, “A Single-Phase On-Board Two-Stage Integrated Battery Charger for EVs Based on Five-Phase Hybrid-Excitation Flux-Switching Machine,” IEEE Trans.on Vehicular Technology, vol.69, no.4, Apr.2020. [3] Khan, Mehnaze Akhter, Iqbal Husain, and Yilmaz Sozer. "Integrated electric motor drive and power electronics for bidirectional power flow between the electric vehicle and DC or AC grid." IEEE Transactions on Power Electronics 28.12(2013):5774-5783. [4] Subotic, Ivan, and Emil Levi. "A review of single-phase on-board integrated battery charging topologies for electric vehicles." 2015 IEEE Workshop on Electrical Machines Design, Control and Diagnosis (WEMDCD). IEEE, 2015. Summary of the Invention [Problem to be solved by the invention]

[0012] The present disclosure provides an on-board charger with an integrated motor drive that can reduce the number of components in an electric vehicle's electrical system. In an electric vehicle, the electrical system includes a motor, a motor drive, and an on-board charger. In charging mode, the on-board charger performs three main functions: power factor correction, isolation, and current regulation. In conventional systems, each component in the electrical system performs a single function. Therefore, the motor and motor drive inverter are not used in charging mode. Meanwhile, the on-board charger is not used in driving mode. The converter topology disclosed herein utilizes the motor and motor drive inverter as part of the on-board charger in charging mode to reduce the number of components in the electrical system. According to an embodiment of the present invention, the motor and motor drive inverter can provide power factor correction and current regulation functions in charging mode by reconfiguring the topology with a relay. Therefore, the disclosed on-board charger with an integrated motor drive can reduce the number of components in the on-board charger, thereby improving the cost-effectiveness of the electrical system. [Means for solving the problem]

[0013] In one aspect, an embodiment of the present disclosure provides an electrical system for an electric vehicle including an AC / DC converter, a motor drive including a motor and an inverter, a power factor correction (PFC) inductor electrically connected between the AC / DC converter and the motor drive, a link capacitor connected in parallel with the motor drive, a first relay connected between the PFC inductor and the motor drive, and a second relay for connecting a battery to the link capacitor.

[0014] In one embodiment, the motor includes a plurality of phases, the inverter includes a plurality of phase legs, and a first end of each of the phases is connected to a respective one of the phase legs.

[0015] In one embodiment, the second end of the phase is connected to a neutral point. In one embodiment, the PFC inductor is connected to a selected one of the phase legs via the first relay.

[0016] In one embodiment, the phase legs include two switches, and the PFC inductor is connected to a terminal between the two switches of a selected one of the phase legs via the first relay.

[0017] In one embodiment, in drive mode, the first relay is open and the second relay is closed, allowing the battery to be discharged to power the motor.

[0018] In one embodiment, in a charging mode, the first relay and the second relay are closed and an AC power source can be used to charge the battery.

[0019] In one embodiment, the AC / DC converter includes an LLC series resonant converter capable of receiving AC power at an input terminal and generating DC power at an output terminal.

[0020] In one embodiment, the AC / DC converter comprises an isolated AC / DC rectifier having a half-bridge inverter and a full-bridge rectifier, an isolated AC / DC rectifier having a full-bridge inverter and a full-bridge rectifier, an isolated AC / DC rectifier having a half-bridge inverter and a voltage doubler rectifier, and Full It includes one of an isolated AC / DC rectifier having a bridge inverter and a voltage doubler rectifier.

[0021] According to one aspect of one embodiment of the present disclosure, there is provided an electrical system for an electric vehicle. The electrical system includes an AC / DC converter, a motor drive device including a motor and an inverter, a power factor correction (PFC) inductor electrically connected between the AC / DC converter and the motor drive device, a link capacitor connected in parallel with the motor drive device, a first relay, and a second relay. The motor includes a plurality of phases, and the inverter includes a plurality of phase legs, each of which is connected to a corresponding one of the phase legs. The first relay is configured to selectively connect a selected one of the phase legs to either a corresponding one of the phases of the motor or the PFC inductor, and the second relay is configured to selectively connect a battery to either a positive terminal of the inverter or the corresponding one of the phases of the motor.

[0022] In one embodiment, each phase leg of the inverter includes two switches, and the first relay is connected between the PFC inductor and a terminal between the two switches of the selected one of the phase legs.

[0023] In one embodiment, one end of the phase legs is connected to one another at a neutral point.

[0024] In one embodiment, the first and second relays comprise single-pole, double-throw relays.

[0025] In one embodiment, in a drive mode, the first relay connects the selected one of the phase legs to the corresponding one of the phases of the motor, and the second relay connects the battery to the positive terminal of the inverter, allowing the battery to be discharged to supply power to the motor.

[0026] In one embodiment, in a charging mode, the first relay connects the selected one of the phase legs to the PFC inductor, and the second relay connects the battery to the corresponding one of the phases of the motor, allowing the battery to be charged using an AC power source.

[0027] In one embodiment, the AC / DC converter includes an LLC series resonant converter capable of receiving AC power at an input terminal and generating DC power at an output terminal.

[0028] In one embodiment, the AC / DC converter comprises an isolated AC / DC rectifier having a half-bridge inverter and a full-bridge rectifier, an isolated AC / DC rectifier having a full-bridge inverter and a full-bridge rectifier, an isolated AC / DC rectifier having a half-bridge inverter and a voltage doubler rectifier, and Full It includes one of an isolated AC / DC rectifier having a bridge inverter and a voltage doubler rectifier.

[0029] According to one aspect of one embodiment of the present disclosure, there is provided an electric vehicle electrical system including an AC / DC converter, a motor drive device including a motor and an inverter, a power factor correction (PFC) inductor electrically connected between the AC / DC converter and the motor drive device, a link capacitor connected in parallel with the motor drive device, a first relay, a second relay, and a third relay, wherein the motor includes a plurality of phases, the inverter includes a plurality of phase legs, each of the phases is connected to a corresponding one of the phase legs, the first relay is connected between a selected one of the phase legs and the corresponding one of the phases, the second relay is configured to connect or disconnect the selected one of the phase legs to the PFC inductor and to connect or disconnect the corresponding one of the phases to a buffer capacitor, and a battery of the electric vehicle is connected to the link capacitor via the third relay.

[0030] In one embodiment, the second relay comprises a double-pole, double-throw relay.

[0031] In one embodiment, in drive mode, the first and third relays are closed and the second relay is open, allowing the battery to be discharged to power the motor.

[0032] In one embodiment, in a charging mode, the second and third relays are closed and the first relay is open, allowing the battery to be charged using AC power.

[0033] According to one aspect of another embodiment of the present disclosure, there is provided an electrical system for an electric vehicle including an AC / DC converter capable of receiving AC power at input terminals of the AC / DC converter and supplying DC power at output terminals of the AC / DC converter, a first relay electrically connected to the output terminals of the AC / DC converter, a motor connected to the AC / DC converter via the first relay, a motor drive inverter connected to the motor, a link capacitor connected in parallel with the motor drive inverter, and a second relay for connecting the link capacitor to a battery.

[0034] In one embodiment, in drive mode, the first relay is open and the second relay is closed, allowing the battery to be discharged to power the motor.

[0035] In one embodiment, in a charging mode, the first relay and the second relay are closed and the AC power source can be used to charge the battery.

[0036] In one embodiment, the motor includes a plurality of phase legs, one end of each of the phase legs being connected at a neutral point, and the first relay being connected to the neutral point.

[0037] In one embodiment, the electrical system further includes a third relay electrically connected to the first relay, the motor, and the motor drive inverter.

[0038] In one embodiment, the motor includes multiple phases, the motor drive inverter includes multiple phase legs, and one of the phases of the motor is connected to a corresponding one of the phase legs of the motor drive inverter via the third relay. In a drive mode, the first relay is open, and the second and third relays are closed, allowing the battery to be discharged to power the motor. In a charge mode, the first and second relays are closed, and the third relay is open, allowing the battery to be charged using the AC power source.

[0039] The present invention will be better understood after consideration of the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0040] [Figure 1A] 1 shows a schematic diagram of a conventional electrical system for an electric vehicle. [Figure 1B] 1B illustrates the direction of electrical energy flow within the system of FIG. 1A in drive mode. [Figure 1C] 1B illustrates the direction of electrical energy flow within the system of FIG. 1A in battery charging mode. [Figure 2A] 1 shows an exemplary schematic circuit of a conventional electrical system for an electric vehicle with a three-phase motor. [Figure 2B] 2B illustrates the driving mode of the conventional electrical system of FIG. 2A. [Figure 2C] 2B illustrates a battery charging mode of the conventional electrical system of FIG. 2A. [Figure 3A] 1 shows a schematic diagram of an electrical system of an electric vehicle having an on-board charger with an integrated motor drive according to the present disclosure; [Figure 3B] 3B illustrates the direction of electrical energy flow in the system of FIG. 3A in drive mode. [Figure 3C] 3B illustrates the direction of electrical energy flow in the system of FIG. 3A in battery charging mode. [Figure 4A] 1 illustrates an electrical system of an electric vehicle having an on-board charger integrated with a motor drive according to a first embodiment of the present disclosure. [Figure 4B] 4B shows a driving mode of the motor drive device integrated on-board charger shown in FIG. 4A. [Figure 4C] 4B shows a battery charging mode of the motor drive device integrated on-board charger shown in FIG. 4A. [Figure 5A] 1 illustrates an electrical system for an electric vehicle having an on-board charger integrated with a motor drive according to a second embodiment of the present disclosure. [Figure 5B] 5B shows a driving mode of the motor drive device integrated on-board charger shown in FIG. 5A. [Figure 5C] 5B shows a battery charging mode of the motor drive device integrated on-board charger shown in FIG. 5A. [Figure 6A] 10 illustrates an electrical system for an electric vehicle having an on-board charger integrated with a motor drive according to a third embodiment of the present disclosure. [Figure 6B] 6B shows a driving mode of the motor driving device integrated on-board charger shown in FIG. 6A. [Figure 6C] 6B shows a battery charging mode of the motor drive device integrated on-board charger shown in FIG. 6A. [Figure 6D] For greater clarity, a simplified version of FIG. 6C is shown. [Figure 7A] 10 illustrates an electrical system for an electric vehicle having an on-board charger integrated with a motor drive according to a fourth embodiment of the present disclosure. [Figure 7B] 7B shows a driving mode of the motor driving device integrated on-board charger shown in FIG. 7A. [Figure 7C] 7B shows a battery charging mode of the motor drive device integrated on-board charger shown in FIG. 7A. [Figure 7D] For greater clarity, a simplified version of FIG. 7C is shown. [Figure 7E] 7C and 7D show control diagrams for the converters of FIG. [Figure 8A] 1 shows the electrical system of an electric vehicle with an on-board charger integrated with a motor drive with a variation of the isolated AC / DC rectifier topology. [Figure 8B]1 shows the electrical system of an electric vehicle with an on-board charger integrated with a motor drive with a variation of the isolated AC / DC rectifier topology. [Figure 8C] 1 shows the electrical system of an electric vehicle with an on-board charger integrated with a motor drive with a variation of the isolated AC / DC rectifier topology. [Figure 8D] 1 shows the electrical system of an electric vehicle with an on-board charger integrated with a motor drive with a variation of the isolated AC / DC rectifier topology. [Figure 9A] 10 illustrates an electrical system of an electric vehicle having an on-board charger integrated with a motor drive according to a fifth embodiment of the present disclosure. [Figure 9B] 9B shows a driving mode of the motor driving device integrated on-board charger of the embodiment shown in FIG. 9A. [Figure 9C] 9B illustrates a battery charging mode of the motor drive device-integrated on-board charger of the embodiment illustrated in FIG. 9A. DETAILED DESCRIPTION OF THE INVENTION

[0041] 3A shows a schematic diagram of an electric vehicle electrical system 30 having an integrated motor drive and on-board charger 34 according to one embodiment of the present disclosure. To reduce parts count, the integrated motor drive and on-board charger 34 provides the functionality of both a motor drive and an on-board charger. This integrated structure is possible because the motor drive and on-board charger do not operate simultaneously. In drive mode, the electrical system 30 operates as a motor drive. In battery charging mode, the electrical system 30 operates as an on-board charger.

[0042] 3B and 3C show the direction of electrical energy flow in system 30 in drive mode and battery charge mode, respectively. In drive mode, as shown in FIG. 3B, electrical energy is supplied from battery 33 to motor 31. Battery 33 is discharging and AC input 35 is disconnected. In battery charge mode, as shown in FIG. 3C, electrical energy is supplied from external AC input 35 to battery 33. Battery 33 is charging. This feature is a key difference between the conventional approach and the motor drive integrated on-board charger approach. In the motor drive integrated on-board charger approach, the motor 31 and components within motor drive integrated on-board charger 34 operate as part of the on-board charger, thereby reducing the component count of the on-board charger.

[0043] 4A shows an electrical system 40 of an electric vehicle with an integrated motor drive and on-board charger according to a first embodiment of the present disclosure. As shown, the electrical system 40 includes a motor 41, a motor drive inverter 42, a battery 43, an isolated AC / DC converter 44, and an external AC power input 45. In one embodiment, the motor 41 includes three motor windings (a three-phase motor), all of which are connected together at a neutral point.

[0044] The isolated AC / DC converter 44 includes rectifier diodes D1, D2, D3, and D4, an input capacitor C IN1 , and LLC converters. LLC converters consist of two switches S INV1 and S INV2 , resonant inductor L R , resonant capacitor C R1 and C R2 , transformer TR, rectifier diode D R1 and D R2 , and Biko Capacitor C IN2 Contains .Ko Capacitor C IN2 is connected to the neutral point of the motor 41 via a relay R1. Chi SEach end of the motor winding of the motor 41 facing the neutral point may include switches S1, S2, S3, S4, S5, and S6. Chi S The motor drive inverter 42 is connected to two of S1, S2, S3, S4, S5, and S6. O The battery 43 is connected in parallel with the link capacitor C via a relay R2. O Compared to the conventional system of FIG. 2A, converter 44 of the embodiment of FIG. 4A has a boost inductor L PFC , switch S B1 , diode D5, and capacitor C O,PFC , thereby reducing the cost of the system.

[0045] 4B and 4C illustrate the drive mode and battery charging mode, respectively, of the on-board charger with integrated motor drive shown in FIG. 4A. In one embodiment, in drive mode, as shown in FIG. 4B, relay R1 is open and relay R2 is closed, connecting the battery 43 only to the motor 41 and motor drive inverter 42, and the isolated AC / DC converter 44 is turned off. Note that the electrical connections of the electrical system 40 in FIG. 4B are substantially identical to the electrical connections shown in FIG. 2B. In charge mode, as shown in FIG. 4C, both relays R1 and R2 are closed, allowing electrical energy to flow from the AC power input 45 to the battery 43. Note that both the motor 41 and the motor drive inverter 42 are part of the charging system. In contrast, in the electrical system 20 in FIG. 2B, the motor 41 and the motor drive inverter 42 are not used during charge mode.

[0046] In this embodiment, in charging mode, the LLC converter of the isolated AC / DC converter 44 is used as an AC / DC rectifier to provide isolation and scaling of the AC power input 45. The switching frequency of the LLC converter is controlled by the resonant tank component L R , C R1 , and C R2The resonant frequency can be varied from half to five times the resonant frequency determined by the following equation: Note that the switching frequency is much higher than the AC input line frequency (e.g., 60 Hz). ,Ko Capacitor C IN2 The voltage across the AC , which is a scaled absolute value of . The motor drive inverter 42 and the three windings of the motor 41 can be viewed as three independent boost converters connected in parallel to operate as a combined boost power factor correction circuit. This allows the circuit of FIG. 4C to provide isolation and power factor correction with a low component count. However, in this embodiment, the electrical system 40 of FIG. 4C may experience large ripples in the charging current due to the output voltage ripple of the PFC circuit. Therefore, in some embodiments, the electrical system 40 of FIG. 4C is applicable to systems where such battery current ripple is acceptable.

[0047] One advantage of the on-board charger with integrated motor drive shown in Figure 4C is that it offers simple control. IN1 is relatively small, so the voltage across it is equal to the input voltage V AC The input capacitor C IN1 sets the voltage across the LLC resonant converter. The resonant converter operates at a 50% duty cycle, constant switching frequency, and the number of turns in the secondary winding of the transformer TR is small compared to the number of turns in the primary winding, so the input capacitor C IN1 The switching frequency of the LLC converter is determined by the battery voltage, battery current, and input voltage V AC Based on the appropriate level of AC voltage Woko Capacitor C IN2 The input capacitor C IN1 as well as ,Ko Capacitor C IN2 The value of the capacitor C IN2 The voltage across the ACSince the AC / DC converter 44 does not have a significant energy storage, both capacitor voltages are equal to the input voltage V AC Such a system can be described as having a soft DC link, as opposed to systems that use larger capacitance values ​​to hold the DC link at a quasi-constant value (e.g., electrical system 20 of FIG. 2A).

[0048] The three-phase motor drive inverter phase legs are controlled so that the current drawn by each motor winding is equal to one another. The current reference for the motor windings is ,Ko Capacitor C IN2 follows the shape of the voltage across the ,Ko Capacitor C IN2 The voltage across is a rectified sine wave. ,Ko Capacitor C IN2 When the voltage across V is zero, no current is drawn from it. As a result, the voltage and current waveforms at the output of the AC / DC converter 44 are both rectified sine waves with the same frequency and alignment. Since the AC / DC converter 44 does not have a significant energy storage, the input power is equal to the output power. Furthermore, the input current of the AC / DC converter 44 is also a rectified sine wave. Therefore, the input current drawn from the grid is equal to the input voltage V AC The phase winding current reference has the same shape and angle as the current reference. Therefore, the proposed converter provides power factor correction. The magnitude of the phase winding current reference depends on the battery charging algorithm. As the battery depletes, the magnitude of the current reference approaches the maximum supported by the converter's power handling capability. As the battery approaches maximum state of charge, the magnitude of the current reference gradually decreases to zero.

[0049] Furthermore, even though all windings carry time-varying currents, the configuration of the embodiment shown in Figure 4C does not generate pulsating torque because all winding currents are equal. This is made possible by the external motor neutral connection. When all three winding currents are equal, the motor carries only zero-sequence current, which does not generate steady-state or low-frequency torque that would cause motor oscillations. The only torque component generated in the system is a small switching-frequency ripple torque due to winding ripple current. Ripple current is inversely proportional to both the motor inductance and the switching frequency.

[0050] 5A illustrates an electrical system 50 for an electric vehicle with an on-board charger and integrated motor drive according to a second embodiment of the present disclosure. Instead of three motor windings connected in parallel, the electrical system 50 of FIG. ,Ko Capacitor C IN2 4A, except that the three-phase motor 51 further includes an external PFC choke 56 for drawing current from the three-phase motor 51. Also, the three-phase motor 51 is connected differently than the motor 41 of FIG. Chi S 1, S2, S3, S4, S5, and S6, and the link capacitor C O In this configuration, the first motor drive inverter phase leg, including switches S1 and S2, is considered to be part of a motor drive system 52 including an external power factor correction (PFC) inductor L PFC In this embodiment, the PFC inductor L PFC includes a boost inductor. Because the three-phase motor 51 remains connected, the other two phase legs operate at the same duty cycle, maintaining zero motor winding current. The approach shown in FIG. 5A has the advantage over the approach in FIG. 4A that it does not require access to the motor's neutral terminal. Conversely, in some embodiments, an additional inductor may be required.

[0051] 5B and 5C respectively show the driving mode and the battery charging mode of the on-board charger with integrated motor drive device shown in FIG. 5A. In the driving mode, as shown in FIG. 5B, relay R1 opens and relay R2 closes, so that the battery is 51 and motor drive inverter 52 connected to the isolated AC / DC converter Ta is It should be noted that the electrical connections of electrical system 50 in Figure 5B are substantially identical to the electrical connections shown in Figure 2B. In charging mode, as shown in Figure 5C, both relays R1 and R2 are closed, allowing electrical energy to flow from the AC power input to the battery.

[0052] In drive mode, as shown in Figure 5B, electrical system 50 operates as a motor drive equivalent to those shown in Figures 3B and 4B. In charge mode, the on-board charger with integrated motor drive shown in Figure 5C provides simple control. Input capacitor C IN1 is relatively small, so the voltage across it is equal to the input voltage V AC The input capacitor C IN1 sets the voltage across the LLC resonant converter. The resonant converter operates at a 50% duty cycle, constant switching frequency, and the number of turns in the secondary winding of the transformer TR is small compared to the number of turns in the primary winding, so the input capacitor C IN1 The switching frequency of the LLC converter is determined by the battery voltage, battery current, and input voltage V AC Based on the appropriate level of AC voltage Woko Capacitor C IN2 The input capacitor C IN1 as well as ,Ko Capacitor C IN2 The value of is also small. ,Ko Capacitor C IN2 The voltage across the AC Since the AC / DC converter does not have a large energy storage, both capacitor voltages are equal to the input voltage V ACSuch a system can be described as having a soft DC link, as opposed to systems that use larger capacitance values ​​to hold the DC link at a quasi-constant value (e.g., electrical system 20 of FIG. 2A).

[0053] The first phase motor drive inverter phase leg is PFC Inductor L PFC Current drawn from Gako Capacitor C IN2 The voltage across the ,Ko Capacitor C IN2 When the voltage across V is zero, no current is drawn from it. As a result, the voltage and current waveforms at the output of the AC / DC converter are both rectified sine waves with the same frequency and alignment. Since there is no significant energy storage in the AC / DC converter, the input power is equal to the output power. Moreover, the input current of the AC / DC converter is also a rectified sine wave. Therefore, the input current drawn from the grid is equal to the input voltage V AC The converter has the same shape and angle as the converter shown in Figure 1. Therefore, the converter provides power factor correction characteristics.

[0054] Additionally, the first motor winding remains connected to the first inverter phase leg. To maintain zero current through the motor winding, the second and third motor drive inverter phase legs are modulated with the same duty cycle as the first motor inverter phase leg, or all switches in the second and third inverter phase legs are turned off. Because current in the motor winding is zero, the configuration shown in Figure 5C produces no torque.

[0055] 6A shows an electrical system 60 for an electric vehicle with an integrated motor drive on-board charger according to a third embodiment of the present disclosure. In this embodiment, the electrical system 60 uses a single-pole, double-throw relay R1 to connect the AC terminal (point A) of the first motor drive inverter phase leg (including switches S1 and S2) to the first motor winding of the motor 61 or an external PF C Inductor L PFCA second single-pole double-throw relay R2 is used to connect the positive terminal of battery 63 to either the positive terminal of the motor drive inverter DC link (point B) or the first motor winding of motor 61.

[0056] 6B and 6C respectively show the driving mode and the battery charging mode of the on-board charger with integrated motor drive device shown in FIG. 6A. In the driving mode, as shown in FIG. 6B, relay R1 connects the AC terminal (point A) of the first motor drive inverter phase leg to the first motor winding, and relay R2 connects the positive terminal of battery 63 to the positive terminal (point B) of the motor drive inverter DC link. Isolated AC / DC converter 64 is turned off. This configuration is electrically and functionally equivalent to that shown in Figures 3B, 4B, and 5B.

[0057] In battery charging mode, as shown in Figure 6C, relay R1 connects the AC terminal (point A) of the first motor drive inverter phase leg (including switches S1 and S2) to the external PF C Inductor L PFC and relay R2 connects the positive terminal of battery 63 to the first motor winding of motor 61. This configuration is redrawn in FIG. 6D for clarity. The main difference between this circuit configuration and the configurations shown in FIGS. 4C and 5C is that the configurations of FIGS. 6C and 6D do not use a voltage source V in the DC link. AC The purpose of this is to absorb pulsating input power from the

[0058] The switching frequency of the LLC converter depends on the battery voltage, battery current, and input voltage V AC Based on the appropriate level of AC voltage Woko Capacitor C IN2 As shown in Figures 6C and 6D, the first motor drive inverter phase leg operates as a boost PFC. In this configuration, the first motor drive inverter phase leg, including switches S1 and S2, supplies an external PFC Inductor L PFC It is only responsible for regulating the current flowing through the PFC Inductor L PFC The current reference for ,KoCapacitor C IN2 follows the shape of the voltage across the ,Ko Capacitor C IN2 The voltage across is a rectified sine wave. ,Ko Capacitor C IN2 When the voltage across V is zero, no current is drawn from the capacitor. As a result, the voltage and current waveforms at the output of the AC / DC rectifier are both rectified sine waves with the same frequency and alignment. Since the AC / DC rectifier does not have a significant energy storage, the input power of the isolated AC / DC converter is equal to the output power. Moreover, the input current of the AC / DC rectifier is also a rectified sine wave. Therefore, the input current drawn from the grid is equal to the input voltage V AC The converter has the same shape and angle as the converter shown in Figure 1. Therefore, the converter provides power factor correction characteristics.

[0059] Furthermore, the second and third motor drive inverter phase legs are connected to the second and third motor windings of the motor 61, and the first motor winding is connected to the positive terminal of the battery 63. The three motor windings remain connected at the neutral point. As a result, the second and third motor drive inverter phase legs and the motor 61 constitute an interleaved buck converter. A buck converter, also known as a step-down converter, has an inductive element connected at the output, so the output current is continuous. As a result, the battery charge current can be easily regulated to a constant value with minimal ripple. Therefore, the circuit configurations shown in Figures 6C and 6D provide both PFC functionality at the input and DC current regulation at the output. The mismatch between the varying input power and the constant output power is compensated for by the existing DC link capacitor C O Provided by.

[0060] Even though the currents in the motor windings connected to the second and third inverter legs are equal in magnitude and polarity, and the currents in the remaining windings are twice as large and opposite in polarity, using the motor windings in the configuration shown in Figures 6C and 6D results in no low-frequency pulsating torque because all windings carry DC current with very little high-frequency ripple. Ripple current is inversely proportional to both the motor inductance and the switching frequency.

[0061] 7A shows an electrical system 70 for an electric vehicle having an on-board charger integrated with a motor drive according to a fourth embodiment of the present disclosure. In this embodiment, a single-pole, single-throw relay R1 connects or disconnects the AC terminal (point A) of the first motor drive inverter phase leg (including switches S1 and S2) from the first motor winding of the motor 71. Additionally, a double-pole, double-throw relay R2 connects the AC terminal (point A) of the first motor drive inverter phase leg to the external PF C Inductor L PFC and the first motor winding is connected or disconnected from the buffer capacitor C B Connect or disconnect with.

[0062] Figures 7B and 7C show the driving mode and battery charging mode, respectively, of the on-board charger with integrated motor drive shown in Figure 7A. In the driving mode, as shown in Figure 7B, relays R1 and R3 are closed and relay R2 is open. The AC terminal (point A) of the first motor drive inverter phase leg is connected to the first motor winding of motor 71. The isolated AC / DC converter is turned off. This configuration is electrically and functionally equivalent to those shown in Figures 3B, 4B, 5B, and 6B.

[0063] In battery charging mode, relay R1 is open, and relays R2 and R3 are closed, as shown in Figure 7C. Relay R2 connects the AC terminal of the first motor drive inverter phase leg (point A) to the external PF C Inductor L PFC and the first motor winding of the motor 71 is connected to a buffer capacitor C B This configuration is redrawn in FIG. 7D for clarity. The main difference between this circuit configuration and the configurations shown in FIGS. 4C, 5C, and 6C is that the configurations of FIGS. 7C and 7D do not use a buffer capacitor C B Voltage source V in AC The purpose of this is to absorb pulsating input power from the

[0064] The switching frequency of the LLC converter depends on the battery voltage, battery current, and input voltage VAC Based on the appropriate level of AC voltage Woko Capacitor C IN2 As shown in Figures 7C and 7D, the first motor drive inverter phase leg operates as a boost PFC. In this configuration, the first motor drive inverter phase leg, including switches S1 and S2, supplies an external PFC Inductor L PFC It is only responsible for regulating the current flowing through the PFC Inductor L PFC The current reference for ,Ko Capacitor C IN2 follows the shape of the voltage across the ,Ko Capacitor C IN2 The voltage across the capacitor C is a rectified sine wave. IN2 When the voltage across V is zero, no current is drawn from the capacitor. As a result, the voltage and current waveforms at the output of the AC / DC rectifier are both rectified sine waves with the same frequency and alignment. Since the AC / DC rectifier does not have a significant energy storage, the input power of the isolated AC / DC converter is equal to the output power. Moreover, the input current of the AC / DC rectifier is also a rectified sine wave. Therefore, the input current drawn from the grid is equal to the input voltage V AC The converter has the same shape and angle as the converter shown in Figure 1. Therefore, the converter provides power factor correction characteristics.

[0065] Additionally, the second and third motor drive inverter phase legs are connected to the second and third motor windings of the motor 71, and the first motor winding is connected to a buffer capacitor C B The three motor windings remain connected at the neutral point. Thus, the second and third motor drive inverter phase legs and the motor 71 constitute an interleaved buck converter. A buck converter, also known as a step-down converter, has an inductive element connected at the output, so the output current is continuous. The buck converter and buffer capacitor C B The combination of these constitutes an active power filter (APF).

[0066] By definition, an active power filter can only supply AC power. Therefore, an active power filter can supply AC power of the same magnitude and opposite polarity as a PFC circuit that supplies both DC and AC power. As a result, the AC component of the PFC circuit is effectively canceled at the battery terminals, resulting in low or no battery current ripple. If the energy supplied by the boost PFC is in excess, the energy is transferred to the link capacitor C O is drawn from the buffer capacitor C B On the other hand, if the energy provided by the boost PFC is insufficient, the energy is stored in the buffer capacitor C B is drawn from the link capacitor C O This allows the output current to be controlled to a constant value. Therefore, the circuit configurations shown in Figures 7C and 7D provide both PFC functionality at the input and low battery current ripple.

[0067] It should also be noted that the configuration of the embodiment shown in Figures 7C and 7D does not disconnect the DC link to the battery 73. Therefore, capacitors and switches are not required to support the slightly higher voltage levels as in the configurations shown in Figures 6C and 6D. Furthermore, even though the currents in windings phase A and phase B are equal in magnitude and polarity, and the current in winding phase C is twice as large and opposite in polarity, using the motor windings in the configurations shown in Figures 7C and 7D does not produce pulsating torque because all windings carry DC current with very small, high-frequency ripple. Ripple current is inversely proportional to both the motor inductance and the switching frequency.

[0068] Figure 7E shows the control diagram of the converter of Figures 7C and 7D. As shown in Figure 7E, the control of the circuits of Figures 7C and 7D is based on two current loops and one voltage loop. The first current loop is ,Ko Capacitor C IN2 So that the voltage at both ends of PFC Inductor L PFCThe first current loop regulates the current through the APF capacitor. This circuit therefore achieves the PFC function. The second current loop regulates the APF current to effectively cancel the AC ripple provided by the PFC circuit. In this embodiment, the APF capacitor voltage must be balanced at a nominal point so that the APF circuit can source or absorb the required power. This is the remaining voltage loop. The voltage loop is designed to be moderately slow, with a crossover frequency of approximately 10 Hz, so as not to interact with the faster APF current loop.

[0069] 8A, 8B, 8C, and 8D show electrical systems for electric vehicles with an on-board charger integrated with a motor driver, with various topology variations of the isolated AC / DC rectifier. For simplicity, only a series resonant converter topology is shown in this disclosure. Note that any type of resonant topology can be used as the isolated AC / DC rectifier stage. The motor and motor drive inverter configuration following the rectifier can be any of the configurations shown in FIGS. 4 to 7.

[0070] Figure 8A shows an on-board charger integrated with a motor drive having an isolated AC / DC rectifier with a half-bridge inverter and a full-bridge rectifier, Figure 8B shows an on-board charger integrated with a motor drive having an isolated AC / DC rectifier with a full-bridge inverter and a full-bridge rectifier, Figure 8C shows an on-board charger integrated with a motor drive having an isolated AC / DC rectifier with a half-bridge inverter and a voltage doubler rectifier, and Figure 8D shows an on-board charger integrated with a motor drive having an isolated AC / DC rectifier with a full-bridge inverter and a voltage doubler rectifier.

[0071] FIG. 9A is a first example of the present disclosure. 51 illustrates an electrical system for an electric vehicle with an integrated motor drive and on-board charger, according to an embodiment. As shown, the electrical system includes a motor, a motor drive inverter, a battery, an isolated AC / DC converter, and an external AC power input. In one embodiment, the motor is a three-phase motor including three motor windings, one of which is connected at the neutral point.

[0072] The isolated AC / DC converter consists of rectifier diodes D1, D2, D3, and D4, and an input capacitor C IN1 , and LLC converters. LLC converters consist of two switches S INV1 and S INV2 , resonant inductor L R , resonant capacitor C R1 and C R2 , transformer TR, rectifier diode D R1 and D R2 , and Biko Capacitor C IN2 Contains .Ko Capacitor C IN2 is connected to the first phase winding of the motor through relay R1. The same winding is connected to the first phase leg of the motor drive inverter through relay R3. The motor drive inverter may include switches S1, S2, S3, S4, S5, and S6. Each end of the motor winding of the motor opposite the neutral point is connected to two of the switches S1, S2, S3, S4, S5, and S6 of the motor drive inverter. The motor drive inverter is connected to a link capacitor C O The battery is connected in parallel with the link capacitor C O Compared to the conventional system of FIG. 2A, the converter of the embodiment of FIG. 9A PFC Inductor L PFC , boost switch S B1 , diode D5, and capacitor C O,PFC This reduces the cost of the system.

[0073] 9B and 9C respectively illustrate the driving mode and battery charging mode of the embodiment of the on-board charger with integrated motor drive shown in FIG. 9A. In the driving mode, as shown in FIG. 9B, relay R1 is open and relays R2 and R3 are closed, connecting the battery only to the motor and motor drive inverter, and the isolated AC / DC converter is turned off. Note that the electrical connections of the electrical system in FIG. 9B are substantially identical to the electrical connections shown in FIG. 2B. In the charging mode, as shown in FIG. 9C, both relays R1 and R2 are closed and relay R3 is open, allowing electrical energy to flow from the AC power input to the battery. Note that both the motor and the motor drive inverter are part of the charging system. In contrast, in the electrical system of FIG. 2B, the motor and motor drive inverter are not used during the charging mode.

[0074] In this embodiment, in charging mode, the LLC converter of the isolated AC / DC converter is used as an AC / DC rectifier to provide isolation and scaling of the AC power input. The switching frequency of the LLC converter is controlled by the resonant tank component L R , C R1 , and C R2 The resonant frequency can be varied from half to five times the resonant frequency determined by the following equation: Note that the switching frequency is much higher than the AC input line frequency (e.g., 60 Hz). ,Ko Capacitor C IN2 The voltage across the ACThe motor drive inverter and the three windings of the motor can be considered as two independent boost converters connected in parallel, operating as a combined boost power factor correction circuit with the first motor winding connected in series with the second and third motor windings. Relay R3 is open, leaving the first phase leg inactive. This allows the circuit of FIG. 9C to provide isolation and power factor correction with a reduced component count. However, the electrical system of FIG. 9C generates a large ripple in the charging current due to the output voltage ripple of the PFC circuit. Therefore, the electrical system of FIG. 9C is applicable to systems where such battery current ripple is acceptable. Compared to the system shown in FIG. 4, this embodiment uses relay R3 but does not require access to the motor winding neutral point.

[0075] One advantage of the on-board charger with integrated motor drive shown in Figure 9C is that it offers simple control. IN1 is relatively small, so the voltage across it is equal to the input voltage V AC The input capacitor C IN1 sets the voltage across the LLC resonant converter. The resonant converter operates at a 50% duty cycle, constant switching frequency, and the number of turns in the secondary winding of the transformer TR is small compared to the number of turns in the primary winding, so the input capacitor C IN1 The switching frequency of the LLC converter is determined by the battery voltage, battery current, and input voltage V AC Based on the appropriate level of AC voltage Woko Capacitor C IN2 The input capacitor C IN1 as well as ,Ko Capacitor C IN2 The value of the capacitor C IN2 The voltage across the AC Since the AC / DC converter does not have a large energy storage, both capacitor voltages are equal to the input voltage V ACSuch a system can be described as having a soft DC link, as opposed to a system that uses larger capacitance values ​​to hold the DC link at a quasi-constant value (e.g., the electrical system of Figure 2A).

[0076] The second and third phase motor drive inverter phase legs are controlled so that the currents drawn by the second and third motor windings are equal to each other. The sum of these two currents is the current in the first motor winding. The current reference for the motor windings is ,Ko Capacitor C IN2 follows the shape of the voltage across the ,Ko Capacitor C IN2 The voltage across is a rectified sine wave. ,Ko Capacitor C IN2 When the voltage across V is zero, no current is drawn from it. As a result, the voltage and current waveforms at the output of the AC / DC converter are both rectified sine waves with the same frequency and alignment. Since there is no significant energy storage in the AC / DC converter, the input power is equal to the output power. Moreover, the input current of the AC / DC converter is also a rectified sine wave. Therefore, the input current drawn from the grid is equal to the input voltage V AC The phase winding current reference has the same shape and angle as the current reference. Therefore, the proposed converter provides power factor correction. The magnitude of the phase winding current reference depends on the battery charging algorithm. As the battery depletes, the magnitude of the current reference approaches the maximum supported by the converter's power handling capability. As the battery approaches maximum state of charge, the magnitude of the current reference gradually decreases to zero.

[0077] It should be noted that for purposes of describing and defining the present disclosure, terms of degree (e.g., "substantially," "slightly," "about," "equivalent," etc.) may be used herein to express the inherent degree of uncertainty that may result from quantitative comparisons, values, measurements, or other expressions. Such terms of degree may be used herein to express the extent to which a quantitative expression can vary from the stated standard (e.g., about 10% or less) without resulting in a change in the basic functionality of the subject matter at issue. Unless otherwise stated herein, numerical values ​​set forth in the present disclosure are deemed to be modified by terms of degree (e.g., "about") to reflect their inherent uncertainty.

Claims

1. an AC / DC converter; a motor drive device including a motor and an inverter, wherein the motor includes a plurality of phases, the inverter includes a plurality of phase legs, and each of the phases is connected to a corresponding one of the phase legs; a power factor correction (PFC) inductor electrically connected between the AC / DC converter and the motor drive; a link capacitor connected in parallel with the motor drive device; a first relay configured to selectively connect a selected one of the phase legs to either a corresponding one of the phases of the motor or the PFC inductor; a second relay configured to selectively connect a battery to either the positive terminal of the inverter or the corresponding one of the phases of the motor; and 2. The electrical system of an electric vehicle, including:

2. 2. The electrical system of claim 1, wherein each of the phase legs includes two switches, the first relay is connected between the PFC inductor and a terminal between two switches of the selected one of the phase legs, and one ends of the phase legs are connected to each other at a neutral point.

3. 2. The electrical system of claim 1, wherein in a drive mode, the first relay connects the selected one of the phase legs to the corresponding one of the phases of the motor, and the second relay connects the battery to a positive terminal of the inverter, allowing the battery to be discharged to supply power to the motor, and in a charge mode, the first relay connects the selected one of the phase legs to the PFC inductor, and the second relay connects the battery to the corresponding one of the phases of the motor, allowing the battery to be charged using an AC power source.

4. an AC / DC converter; a motor drive device including a motor and an inverter, wherein the motor includes a plurality of phases, the inverter includes a plurality of phase legs, and each of the phases is connected to a corresponding one of the phase legs; a power factor correction (PFC) inductor electrically connected between the AC / DC converter and the motor drive; a link capacitor connected in parallel with the motor drive device; a first relay connected between a selected one of the phase legs and a corresponding one of the phases; a second relay configured to connect or disconnect the selected one of the phase legs to or from the PFC inductor and to connect or disconnect the corresponding one of the phases to or from a buffer capacitor; a third relay for connecting a battery to the link capacitor; 2. The electrical system of an electric vehicle, including:

5. 5. The electrical system of claim 4, wherein in a drive mode, the first and third relays are closed and the second relay is open, allowing the battery to be discharged to power the motor, and in a charge mode, the second and third relays are closed and the first relay is open, allowing the battery to be charged using an AC power source.

6. an AC / DC converter capable of receiving AC power at an input terminal of the AC / DC converter and providing DC power at an output terminal of the AC / DC converter; a first relay electrically connected to an output terminal of the AC / DC converter; a motor connected to the AC / DC converter via the first relay; a motor drive inverter connected to the motor; a link capacitor connected in parallel with the motor drive inverter; a second relay for connecting the link capacitor to a battery; Including, the motor includes a plurality of phases, one end of each of the phases is connected to a neutral point, and the first relay is connected to the neutral point via one of the plurality of phases of the motor; an inverter for inverter control, the inverter including a plurality of phase legs, one of the plurality of phases of the motor being connected to a corresponding one of the plurality of phase legs of the motor drive inverter via the third relay, and the inverter for inverter control, the inverter including a plurality of phase legs of the motor being connected to a corresponding one of the plurality of phase legs of the motor drive inverter via the third relay; and

7. 7. The electrical system of claim 6, wherein in a drive mode, the first relay is open and the second relay is closed, allowing the battery to be discharged to power the motor, and in a charge mode, the first relay and the second relay are closed, allowing the AC power source to be used to charge the battery.

8. The electrical system of claim 6, wherein in a drive mode, the first relay is open and the second relay and the third relay are closed, allowing the battery to be discharged to supply power to the motor, and in a charge mode, the first relay and the second relay are closed and the third relay is open, allowing the battery to be charged using the AC power source.

9. 10. The electrical system of claim 1, wherein the AC / DC converter comprises a resonant converter capable of receiving AC power at an input terminal and producing DC power at an output terminal.

10. 2. The electrical system of claim 1, wherein the AC / DC converter comprises one of an isolated AC / DC rectifier having a half-bridge inverter and a full-bridge rectifier, an isolated AC / DC rectifier having a full-bridge inverter and a full-bridge rectifier, an isolated AC / DC rectifier having a half-bridge inverter and a voltage doubler rectifier, and an isolated AC / DC rectifier having a full-bridge inverter and a voltage doubler rectifier.

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